Juliana Ferreira

Long-term follow-up of topical 5-aminolaevulinic acid photodynamic therapy diode laser single session for non-melanoma skin cancer

Photodynamic therapy (PDT) is based on the association of a light source and light sensitive agents in order to cause the selective death of tumor cells. To evaluate topical 5-aminolaevulinic acid (5-ALA) and diode laser photodynamic single session therapy single session for non-melanoma skin cancer (NMSC), a long-term follow-up was performed. Nineteen Bowens disease (BD) and 15 basal cell carcinoma (BCC) lesions were submitted to 6-h topical and occlusive 20% 5-ALA plus DMSO and EDTA, and later were exposed to 630 nm diode laser, 100 or 300 J cm(-2) dose. At 3 months tumor-free rate was 91.2% (31/34) whereas at 60 months, 57.7% (15/26), slightly higher in BCC (63.6%; 7/11). The relation between the reduction of the clinical response and the increase of tumor dimension observed at 18 months was lost at 60 months. The sBCC recurrence was earlier compared to the nBCC one. ALA-PDT offered important advantages: it is minimally invasive, an option for patients under risk of surgical complications; clinical feasibility; treatment of multiple lesions in only one session or lesions in poor healing sites and superior esthetical results. However, the recurrence rate increase after ALA-PDT diode laser single session can be observed at long-term follow-up, and the repetitive sessions, an additional advantage of the method, is strongly recommended. The clinical response and recurrence time seem to be related to the laser light dose and NMSC types/sub-types, thickness and dimension, which must be considered for the choice of the ALA-PDT.

Topical photodynamic therapy for Bowen's disease of the digit in epidermolysis bullosa

nails. She had no prior manicure treatments to the nails or cuticles. After 3 months of daily isotretinoin her rosacea had cleared but the appearance of her nails caused her significant psychological distress and she elected to discontinue isotretinoin. Trimethoprim 200 mg twice daily was commenced but was discontinued due to nausea. She was recommenced on doxycycline 100 mg daily with 0Æ75% metronidazole gel. Three months after discontinuing isotretinoin the nail dystrophy had grown out 3 mm from the proximal nail fold (Fig. 1b). At 6 months her nails had completely returned to normal (Fig. 1c). The patient’s rosacea remains well controlled 9 months after discontinuing isotretinoin. Review of the images suggested that the patient had elkonyxis rather than median nail dystrophy. A diagnosis of isotretinoin-induced elkonyxis was made. Elkonyxis is an unusual nail dystrophy where the nail develops a pinched-out appearance which begins at the lunula and progressively grows out. This rare nail dystrophy has only previously been reported to occur in association with etretinate treatment. Our patient was initially thought to have isotretinoin-induced median nail dystrophy, a rare complication of isotretinoin treatment. However, median nail dystrophy tends to be a symmetrical nail dystrophy with a longitudinal defect in the nail in the centre or just off-centre of the nail with numerous transverse feathery cracks. There may be an associated enlarged lunula present. If the longitudinal defect is prominent and there are prominent multiple transverse nail defects in a ‘fir tree’ or ‘herring bone’ like appearance, the condition is often termed ‘median canaliform (Heller’s) dystrophy’. Median nail dystrophy is thought most commonly to be due to repeated inadvertent or selfinflicted trauma to the proximal nail fold. The cause for retinoid elkonyxis is unknown. Possible mechanisms would include alteration in the formation of keratins within the nail matrix or altered keratinization of the proximal nail fold and ⁄or cuticle (or alternatively the nail bed) which impairs or impinges on the uninterrupted formation of the nail plate. Close inspection of our sequential images demonstrates loss of cuticle early on (Fig. 1a) but re-establishment of a normal cuticle 3 months after discontinuing isotretinoin (Figs 1b,c). This suggests that abnormalities of the cuticle and proximal nail fold may contribute to the formation of elkonyxis. In our case, the temporal onset of elkonyxis after commencing isotretinoin, resolution following discontinuation of isotretinoin and the absence of trauma or other skin disease affecting the proximal nail fold is suggestive of a causal relationship. It is interesting that isotretinoin 20 mg daily (but not at doses of 20 mg twice and thrice weekly) elicited the development of elkonyxis. This suggests that the development of elkonyxis may in part be dose related in susceptible individuals. Elkonyxis is a rare and unusual type of nail dystrophy previously reported with etretinate treatment. Elkonyxis appears to be an idiosyncratic and possibly dosedependent nail dystrophy rarely associated with retinoid therapy.

Cellular aspects of liver regeneration

This paper has the objective to analyze the cellular aspects of liver regeneration (LR). Upon damage in this organ, the regenerative capacity of hepatocyte is sufficiently able to reestablish the parenchyma as a whole. Taking into account the regenerative capacity of hepatocyte, the need of a progenitor or a liver trunk cell was not obvious. Nowadays it is well-established that precursor cells take part in the liver regenerative process. The liver trunk cell, oval cell, acts as a by-potential precursor, contributing for the liver restoration, mainly when the hepatocytes are unable to proliferate. Another precursor, trunk cell of hematopoetic origin (HSC), takes part in the regenerative process, originating cells of the hepatocytic lineage and colangiocytes, as well as the oval cell. The way the trans-differentiation takes place is not established yet. A number of studies must be undertaken in order to clarify questions, such as the possible occurrence of cellular fusion process between the HSC and the hepatic cells and the possibility of application as a new therapeutic procedure in the treatment of diseases associated with insufficiency of this noble organ.

A molecular view of liver regeneration

The purpose of this review was to carry out an analysis of the liver regenerative process focusing on the molecular interactions involved in this process. The authors undertook a review of scientific publications with a focus on the liver regeneration. The cellular processes involved in liver regeneration require multiple systematic actions related to cytokines and growth factors. These interactions result in the initiation of mitogenic potential of the hepatocytes. The action of these modulators in the regenerative process require a processing in the extra-cellular matrix. Serines and metal proteins are responsible for the bio availability of cytokines and growth factors so that they can interact as receptors in the cellular membrane generating signaling events for the beginning and end of the liver regenerative process. The exact mechanism of interaction between cells, cytokines and growth factors is not well established yet. A series of ordered events that result in the hepatic tissue regeneration has been described. The better understanding of these interactions should provide a new approach of the treatment for liver diseases, aiming at inducing the regenerative process.

PDT experience in Brazil: A regional profile.

The success of PDT and its establishment into the existent hall of therapeutic modalities depends on the collection of reported experiences from around the world. In that sense, it is important to report approaches taken by different countries and what their views are on the future of PDT. Following this idea, we present our clinical experience in photodynamic therapy (PDT) in Brazil, as well as the experimental advances coming up in parallel with clinical implementation. This report is a consequence of pioneering work in a collaborative program involving the Physics Institute in São Carlos, São Paulo State (SP), Brazil, the Medical School of the University of São Paulo, Ribeirão Preto, SP, Brazil and the Cancer Hospital Amaral Carvalho, Jaú, SP, Brazil. This collaborative program, begun in 1997, with the first patient treated in 1999, has treated over 400 patients by late 2004. About 80% of lesions were located in the head and neck or skin, but experience is being built in esophagus, bladder, gynecology, and cutaneous recurrence of breast cancer, among others. The overall results have shown to be compatible with previously reported data. Modifications, whose goal is to improve patient benefit and optimize results, are being implemented as we gain experience. In parallel with the clinical development, several laboratories have started studying experimental whose purpose is to analyze the clinical results and to contribute to the worldwide effort to bring PDT to the forefront of therapies offered to patients. We present the overall results of our 5 years experience as well as the whole implementation process.

Can efficiency of the photosensitizer be predicted by its photostability in solution

We have investigated a possible correlation between the photostability and photodynamic efficacy for different photosensitizers; hematoporphyrin derivatives and chlorines. To perform such analysis, we combined the depth of necrosis (dnec) measurement, expressed by the light threshold dose and a photodegradation parameter, measured from investigation of photosensitizer degradation in solution. The dnec analysis allows us to determine the light threshold dose and compare its value with the existent results in the literature. The use of simple models to understand basic features of Photodynamic Therapy (PDT) may contribute to the solid establishment of dosimetry in PDT, enhancing its use in the clinical management of cancers and others lesions. Using hematoporphyrin derivatives and chlorines photosensitizers we investigated their properties related to the photodegradation in solution and the light threshold dose (Dth) in rat livers.

Correlation of cytotoxicity and depth of necrosis of the photoproducts of photogem

Photodynamic therapy (PDT) is an approved modality for cancer treatment, which involves the administration of a photosensitive drug (PS) that is selectively accumulated in neoplastic tissues and their vasculature and subsequently can be activated with light at the appropriate wavelength to generate reactive molecular species that are toxic to tissues. In PDT, a great part of the used PS suffers degradation by light (photobleaching) that involves a decrease in the absorption and intensity of fluorescence of the photosensitizer as well as photoproduct formation evidenced by the appearance of a new absorption band. In this study, we investigated the correlation of cytotoxicity and depth of necrosis of Photogem and its photoproducts obtained previously by irradiation at 514 and 630 nm. The cytotoxicity for degraded Photogem decreases with the previous irradiation time of Photogem solution suggesting that the photoproducts of Photogem are less cytotoxics than the original formulation. A transition between the necrosed epithelium and healthy epithelium of normal liver of rats after irradiation at 630 nm was observed with irradiated and nonirradiated PS. It is observed that the depth of necrosis only at irradiation dose of 150 J/cm2 in both concentrations is greater for Photogem followed by Photogem degradated previously at 514 and then at 630 nm. The results obtained suggest that the threshold of necrosis values is lower for Photogem followed by its photoproducts formed, suggesting that the photoproducts present a low photodynamic activity. If the photosensitizer degradation happens at the same time as tumor destruction, the drug degradation can be complete before reaching the threshold of necrosis; then it is very important to control the drug concentration and light intensity of irradiation during PDT.

Determination of threshold dose of photodynamic therapy to measure superficial necrosis.

BACKGROUND DATA Photodynamic therapy (PDT) involves the photoinduction of cytotoxicity using a photosensitizer agent, a light source of the proper wavelength, and the presence of molecular oxygen. A model for tissue response to PDT based on the photodynamic threshold dose (D(th)) has been widely used. In this model cells exposed to doses below D(th) survive while at doses above the D(th) necrosis takes place. OBJECTIVE This study evaluated the light D(th) values by using two different methods of determination. One model concerns the depth of necrosis and the other the width of superficial necrosis. MATERIALS AND METHODS Using normal rat liver we investigated the depth and width of necrosis induced by PDT when a laser with a gaussian intensity profile is used. Different light doses, photosensitizers (Photogem, Photofrin, Photosan, Foscan, Photodithazine, and Radachlorin), and concentrations were employed. Each experiment was performed on five animals and the average and standard deviations were calculated. RESULTS A simple depth and width of necrosis model analysis allows us to determine the threshold dose by measuring both depth and surface data. Comparison shows that both measurements provide the same value within the degree of experimental error. CONCLUSION This work demonstrates that by knowing the extent of the superficial necrotic area of a target tissue irradiated by a gaussian light beam, it is possible to estimate the threshold dose. This technique may find application where the determination of D(th) must be done without cutting the tissue.

New photonic technologies for the treatment and diagnosis of hepatic diseases: an overview of the experimental work performed in collaboration, between Physics Institute of São Carlos and Ribeirão Preto Faculty of Medicine of the University of São Paulo

Recent advances in optical techniques have created a great range of possibilities for diagnosis and therapeutics in liver related diseases. With the uses of efficient light sources like lasers and LEDs (Light Emitting Diodes) it is possible to employ the light-tissue interaction to promote hepatic tissue regeneration after partial hepatectomy, to detect hepatocarcinoma and steatosis by utilizing optical fluorescence, to evaluate the metabolism of the liver during hepatic transplantation as well as to treat liver tumors. We present here an overview of the technique presently in development at the Ribeirâo Preto Faculty of Medicine-USP in cooperation with the Physics Institute of São Carlos-USP. The results obtained so far have been the subject of a list of publications and are here presented as an overview. A new perspective for modern application of optical techniques in different medical practices related to the liver is presented.

Fluorescence spectroscopy to diagnose hepatic steatosis in a rat model of fatty liver

Background: Steatosis is diagnosed on the basis of the macroscopic aspect of the liver evaluated by the surgeon at the time of organ extraction or by means of a frozen biopsy.